US3450806A - Process and apparatus for the formation of film - Google Patents

Process and apparatus for the formation of film Download PDF

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Publication number
US3450806A
US3450806A US594596A US3450806DA US3450806A US 3450806 A US3450806 A US 3450806A US 594596 A US594596 A US 594596A US 3450806D A US3450806D A US 3450806DA US 3450806 A US3450806 A US 3450806A
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Prior art keywords
film
mandrel
cooling
die
tubular
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Expired - Lifetime
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US594596A
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English (en)
Inventor
Ryota Matsuo
Shido Tanabe
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ExxonMobil Technology and Engineering Co
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Exxon Research and Engineering Co
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
    • B29C48/901—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies
    • B29C48/902—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies internally
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • B29C48/10—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels flexible, e.g. blown foils
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/32—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles
    • B29C48/33—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles with parts rotatable relative to each other
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/911—Cooling
    • B29C48/9115—Cooling of hollow articles
    • B29C48/912—Cooling of hollow articles of tubular films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0018—Combinations of extrusion moulding with other shaping operations combined with shaping by orienting, stretching or shrinking, e.g. film blowing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0019—Combinations of extrusion moulding with other shaping operations combined with shaping by flattening, folding or bending

Definitions

  • Thermoplastic resin film is formed by extruding resin through a ring die, preliminarily cooling the extruded film with a cooling gas, and then passing the film over a mandrel positioned within a cooling liquid bath.
  • the die, mandrel, and bath are connected in a fixed relationship to each other and are rotated simultaneously to randomize film thickness imperfections over a portion of the film surface.
  • This invention relates to a process and the apparatus for efiiciently preparing films, particularly tubular film, from thermoplastic resins, and specifically for preparing a transparent tubular film with a uniform diameter and thickness from a crystalline thermoplastic resin, such as polypropylene.
  • thermoplastic resin is charged from an extrusion machine and is passed generally downwardly from a film die between a vertically disposed film support member and a fixed body or bath of cooling liquid.
  • the film support member makes up one wall of the enclosure for the cooling liquid and the molten film is maintained in contact with at least a portion of the film support member by the pressure of the cooling liquid exerted against the film.
  • the finished film is recoverd by passing the film through an enclosure positioned adjacent to the film support member in the bottom of the cooling bath enclosure.
  • molten substantially tubular film body of thermoplastic resin was again formed using typical extrusion techniques and cooled by causing the tubular film body to slide over a cylindrical cooling mandrel that is positioned in a fixed body or bath of cooling liquid.
  • the outside surface of the tubular film is cooled through contact with the cooling liquid and the inside surface of the film is cooled through at least partial contact with the cooling mandrel during the time the film is caused to slide over the mandrel.
  • the molten tubular film is partially cooled and simultaneously expanded prior to passage over the mandrel by means of a cooling gas, e.g. air or nitrogen, blown against the film on both the inner and outer surfaces of the film body.
  • a cooling gas e.g. air or nitrogen
  • the gas blown from within the tubular film is desirably directed upwardly against the film in the zone where the film first contacts the mandrel.
  • the cooling gas could be directed both upwardly and downwardly against the downwardly forwarded inside surface of the film.
  • the extrusion die, mandrel, and liquid tank be maintained at a fixed relationship to each other and rotated or oscillated simultaneously.
  • it is extremely difiicult to rotate the die and maintain the die in a direction perpendicular to the vertical surfaces of the mandrel and eccentric rotation of the die with respect to the mandrel is unavoidable.
  • FIGURE 1 is a front elevation of an embodiment of the present invention with its main parts shown in crosssection.
  • the extrusion die is made up of outer die 1 and inner die 3.
  • the die members are integrally fixed together and rotatably suspended from the adapter section of a typical extruder (not shown in drawing) by means of thrust bearing 20.
  • a passage 2 for the flow of fused thermoplastic resin.
  • Passage 2 terminates in an annular slit 4 at the bottom of the die.
  • Fused thermoplastic resin is introduced to passage 2 from the extruder through channel 21.
  • Reference numeral 17 designates a metal fitting, the lower end of which is fixed a hollow tubular-shaped mandrel 7.
  • Metal fitting 17 is inserted into a central opening located in inner die 3 and is positioned within the central opening by flange -8 and bolts 9 provided circumferentially around the metal fitting 17.
  • Metal fitting 17 has intake tubeways 5' for the passage of cooling liquid to the mandrel and outlet tubeways 5 for the return of the cooling liquid from the mandrel.
  • the tubeways pass through inserting holes 6 which are bored laterally in the die.
  • Reference numeral designates an external cooling liquid tank or cell that is positioned around the outer periphery of cooling mandrel 7.
  • the cooling mandrel makes up one wall of the enclosure for the cooling liquid.
  • Mandrel 7 projects through the bottom plane of the liquid tank 10.
  • An elastic sealing material 11 is positioned around the outer periphery of the opening in the bottom of the liquid tank 10. The sealing material contacts the outer surface of the cooling mandrel and serves to maintain the cooling liquid within the cooling tank.
  • tubular film 12 is formed by extruding a thermoplastic resin through annular slit 4. The film is simultaneously expanded and preliminarily cooled by means of a cooling gas directed upwardly from the cooling mandrel through means not shown and then passed over cooling mandrel 7. After contact with the cooling mandrel 7 and the cooling liquid maintained in cooling tank 10, the tubular film slides from the cooling zone between the mandrel and elastic seal 11.
  • the liquid tank 10 is suspended from outer die 1 by means of at least three metal fittings 14 which are positioned to outer die 1 by means of bolts 16.
  • the lateral and longitudinal adjustment or alignment of the liquid tank 10 with respect to mandrel 7 is achieved with the use of adjustment bolts 18 and 18'.
  • the extrusion die, mandrel and cooling tank are simultaneously oscillated or rotated through the action of a driving mechanism (not shown) upon sprocket wheel 15.
  • the sprocket wheel and metal fittings 14 are each attached to the outer die by means of bolts 16.
  • the transfer of heat from outer die 1 to the sprocket wheel and fittings 14 is prevented by means of insulation 13.
  • the finished tubular film product 12 is folded into a flatform by means of nip rolls 19. Thereafter, the film is passed to take-up rolls.
  • Film grade crystalline polypropylene is melted in the ordinary manner in a typical extrusion device and is passed in a downward direction through a tubular film die.
  • the molten tubular film is subjected to preliminary cooling prior to contact with the cooling mandrel with a forced cooling gas such as air to partially rigidify the film.
  • the preliminary cooling is effected with air blown over the outside of the film by means of an air-ring placed immediately below the ring die.
  • a compressed cooling gas is blown inside the tubular film to cool the film and also simultaneously expand the film to a diameter slightly larger than that of the mandrel.
  • polypropylene films should be at about 375 to 400 F. and polyethylene films at 300 to 325 F.
  • the tubular film die is rigidly connected to the cooling mandrel and the die is desirably equipped with means to transfer heat exchanging cooling liquid to and from the interior of the cooling mandrel, means to supply compressed cooling gas to the inside of the film to simultaneously expand and partially cool the film prior to it reaching the mandrel, and means to supply compressed gas to the inside of the tubular film when the film is positioned between the mandrel and the take-up nip rolls.
  • cooling liquid flows through the ring die into the mandrel and is discharged. Passage of the cooling liquid through the mandrel maintains the Wall of the mandrel at the desired temperature.
  • the cooling mandrel need not be internally cooled with the use of a circulating liquid since the major portion of the wall of the mandrel is cooled indirectly by the bath of cooling liquid surrounding the tubular film. Generally, it is sufficient merely to agitate a constant supply of liquid maintained within the mandrel with bubbled air or with a stirring apparatus. Water can be conveniently used as the cooling liquid medium maintained in the external bath and for indirectly cooling the mandrel.
  • both the mandrel and the external cooling liquid be maintained at temperatures below about 45 C. Additionally, it is desirable that the level of the cooling liquid in the bath be maintained from about 5 to 35 millimeters above the point of desired initial contact of the film with the mandrel.
  • the level of the outer cooling liquid is at a level less than 5 millimeters above the point of desired initial contact with the mandrel, the inside surface of the film is at a relatively high temperature prior to contact with the mandrel and it is likely that the inside surface of the film will adhere to the mandrel.
  • the level of the external cooling liquid is raised more than 35 millimeters above the point of desired contact of the film with the mandrel, the excessive water pressure force the film against the upper portion of the mandrel, thereby causing the film to wrinkle.
  • cooling mandrel In general when a cooling mandrel is employed in manufacturing tubular film from thermoplast resins, resin decomposition products as well as resin additives such as stabilizers, and slip agents may condense onto the cooling mandrel as a liquid or solid. The condensation of these materials tends to disrupt the process and also serves to cause the formation of opaque spots on the film.
  • compressed cooling gas e.g., air
  • the cooling gas is preferably directed in an upward direction counter to the downward flow of film to expand and partially rigidify the film and also to prevent the condensation of resin decomposition products and resin additives at the contact zone.
  • the use of an upwardly directed stream of cooling gas materially reduces the amount of condensed products at the point of contact of the film with the cooling mandrel.
  • the tubular film body is directed downwardly past an elastic seal positioned at the lower juncture of the cooling mandrel, which makes up one wall of the vessel containing the cooling liquid, and the opening in the main body of the liquid tank. Since loss of cooling liquid from the bottom of the liquid tank is substantially prevented by the liquid seal, the tubular film leaving the cooling mandrel is not accompanied by appreciable amounts of liquid.
  • the degree to which the film die, mandrel and liquid bath are rotated or oscillated is primarily dependent upon the extent to which it is desired to randomize the film thickness variation over the entire surface of the film body.
  • the desirable effect of distributing the film imperfection over the entire surface of the film body can be achieved by either continuously rotating the die, mandrel and water bath at speeds varying from revolutions per minute to revolutions per hour or else by oscillating the die, mandrel and cooling bath such as by rotating the entire mechanism through a desired angle at a desired speed in one direction followed by rotating the apparatus in the opposite direction through the desired angle at the desired speed.
  • the entire apparatus can be oscillated through an angle varying from 45 to 360 in the clockwise direction and then rotated through the same angle in a counterclockwise direction at speeds varying from revolutions per minute to revolutions per hour.
  • the total apparatus is oscillated through an angle varying from 180 to 360.
  • rotating and rotation as used herein are meant to include both operations wherein the entire apparatus is continuously rotated in one direction and operations wherein the entire apparatus is oscillated by rotating the apparatus first in one direction and then in the opposite direction.
  • EXAMPLE 1 Polypropylene having an isotactic content of about 96% and a melt index of 8.2 was extruded in a downward direction using a 65 millimeter extruder through an annular die of 250 millimeter diameter at a temperature of 250 C. A die oscillating apparatus was provided between the adapter section of the extruder and the annular die and the die was oscillated at such a speed as taking about 5 minutes to make one reciprocation within an angle of 180. The cooling mandrel and the cooling liquid tank were fixed to and were oscillated together with the die. The tubular-shaped film formed was collapsed into sheet form and was wound into a roll.
  • the film roll thus formed had a completely parallel tubular shape and n0 variations in the diameter of the roll'were noted as the film surface was parallel to the axis of the roll. Film formation proceeded in a smooth manner and no leaking of the cooling liquid from the cooling liquid tank was observed.
  • the film roll formed did not show a complete parallel tubular shape as a portion of the roll, where the film was thick in the direction of the width of the roll, exhibited a convex surface and another portion of the roll exhibited a concave surface.
  • the film taken from this irregular roll had poor flat characteristics and secondary processing such as printing or forming of the tubular film into bags was very diificult.
  • tubular thermoplastic film comprising extruding a thermoplastic resin generally downwardly through a die in the form of a molten thermoplastic substantially tubular film body, preliminarily cooling said tubular film body to partially rigidify said film, downwardly passing said film to a cooling mandrel, said mandrel positioned in a cell containing a cooling liquid, sliding the inside surface of said tubular film downwardly over the outer surface of said cooling mandrel whereby the inside surface of said tubular film is maintained in contact with at least a portion of said mandrel by the pressure exerted by the cell cooling liquid and is cooled through contact with said mandrel and the outer surface of said film is cooled through contact with said cooling liquid in said cell, and thereafter recovering said tubular film, the improvement which comprises connecting in a fixed relationship to each other, the die, mandrel and cooling liquid cell, and rotating the die, mandrel and cooling liquid cell in said fixed relationship thereby randomizing film thickness imperfections over a portion of the film
  • thermoplastic resin is polypropylene
  • Apparatus for manufacturing tubular film from thermoplastic film forming resinous materials which comprises, in cooperating combination:
  • cooling mandrel and cell for containing a cooling liquid, said cooling mandrel positioned within said cell, said mandrel and cell positioned beneath said die means, said die means, cooling mandrel and cell connected in a fixed relationship to each other;
  • the apparatus of claim 8 including means for expanding said tubular film prior to forwarding said film to said mandrel to a diameter larger than the diameter of said cooling mandrel.
  • the apparatus of claim 9 including means for pre liminarily cooling the outside surface of said tubular film prior to forwarding said film to said mandrel.
  • said means for preliminarily cooling said tubular film and expanding said tubular film comprise means for passing a gas upwardly through the inside portion of said downwardly forwarded tubular film body.
  • tubular thermoplastic film comprising:
  • thermoplastic resin generally downwardly through a die in the form of a molten thermoplastic substantially tubular film body
  • thermoplastic resin is polypropylene
  • tubular thermoplastic film comprising:
  • thermoplastic resin selected from the group consisting of polyethylene and polypropylene generally downwardly through a die in the form of a molten thermoplastic substantially tubular film body
  • Apparatus for manufacturing tubular film from thermoplastic film forming materials which comprises in cooperating combination:
  • cooling mandrel and cell for containing a cooling liquid, said cooling mandrel positioned within said cell, and said mandrel and cell positioned beneath said extruding means, said extruding means, cooling mandrel and cell connected in a fixed relationship to each other;

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
US594596A 1965-11-26 1966-11-15 Process and apparatus for the formation of film Expired - Lifetime US3450806A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP7254165 1965-11-26

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US3450806A true US3450806A (en) 1969-06-17

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US594596A Expired - Lifetime US3450806A (en) 1965-11-26 1966-11-15 Process and apparatus for the formation of film

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US (1) US3450806A (fi)
CH (1) CH456129A (fi)
DE (1) DE1629396C3 (fi)
DK (1) DK119848B (fi)
FI (1) FI46927C (fi)
FR (1) FR1501635A (fi)
GB (1) GB1113300A (fi)
NL (1) NL155476B (fi)
SE (1) SE326026B (fi)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2062789A1 (de) * 1969-12-22 1971-07-01 Exxon Research Engineering Co Verfahren und Vorrichtung zur Herstel lung einer schlauchförrmgen thermoplasti sehen Feinfolie
DE2136168A1 (de) * 1970-07-21 1972-03-23 Bakelite Xylonite Ltd Verfahren und Vorrichtung zur Herstellung von Schläuchen
US3887673A (en) * 1970-07-24 1975-06-03 Showa Denko Kk Apparatus and method for manufacturing tubular film of thermoplastic resin
US3947170A (en) * 1974-04-05 1976-03-30 Windmoller & Holscher Rotary film blowhead for making tubular films of thermoplastic material
US3989785A (en) * 1972-11-21 1976-11-02 The Dow Chemical Company Method for the preparation of plastic film
US4003973A (en) * 1972-06-23 1977-01-18 Kabushiki Kaisha Kohjin Process and apparatus for producing sheet film from tubular thermoplastic resin film
US4112034A (en) * 1977-05-05 1978-09-05 General Electric Company Biaxial film process and rotary apparatus therefor
US4185148A (en) * 1976-05-17 1980-01-22 Mitsubishi Rayon Company Limited Process for producing the polypropylene film for electrical appliances
US4195054A (en) * 1978-04-21 1980-03-25 Teepak, Inc. Method and apparatus for the manufacture of fibrous casing
US4203942A (en) * 1973-01-08 1980-05-20 Exxon Research & Engineering Co. Process for tubular water-bath polypropylene films
US4285899A (en) * 1978-05-17 1981-08-25 Nortene Method and apparatus for making helical plastic members, and the members produced
US6033618A (en) * 1997-08-27 2000-03-07 Kalle Nalo Gmbh & Co. Kg Process and apparatus for producing a seamless cellulose-based tubular film by extrusion

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1295205A (fi) * 1970-07-24 1972-11-08
DE2519705C2 (de) * 1975-05-02 1982-03-18 MFC Maschinenfabrik Chur AG, Chur Vorrichtung zum Strangpressen von Rohren

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB842064A (en) * 1958-09-19 1960-07-20 Metal Box Co Ltd Improvements in or relating to the extrusion of seamless tubes of plastics material
US3092874A (en) * 1961-07-17 1963-06-11 Du Pont Production of thermoplastic polymeric film
US3193547A (en) * 1961-09-07 1965-07-06 Gloucester Eng Co Inc Method and apparatus for extruding plastic
US3400184A (en) * 1964-09-21 1968-09-03 Exxon Research Engineering Co Process and apparatus for preparing film from thermoplastic resins

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB842064A (en) * 1958-09-19 1960-07-20 Metal Box Co Ltd Improvements in or relating to the extrusion of seamless tubes of plastics material
US3092874A (en) * 1961-07-17 1963-06-11 Du Pont Production of thermoplastic polymeric film
US3193547A (en) * 1961-09-07 1965-07-06 Gloucester Eng Co Inc Method and apparatus for extruding plastic
US3400184A (en) * 1964-09-21 1968-09-03 Exxon Research Engineering Co Process and apparatus for preparing film from thermoplastic resins

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2062789A1 (de) * 1969-12-22 1971-07-01 Exxon Research Engineering Co Verfahren und Vorrichtung zur Herstel lung einer schlauchförrmgen thermoplasti sehen Feinfolie
DE2136168A1 (de) * 1970-07-21 1972-03-23 Bakelite Xylonite Ltd Verfahren und Vorrichtung zur Herstellung von Schläuchen
US3887673A (en) * 1970-07-24 1975-06-03 Showa Denko Kk Apparatus and method for manufacturing tubular film of thermoplastic resin
US4003973A (en) * 1972-06-23 1977-01-18 Kabushiki Kaisha Kohjin Process and apparatus for producing sheet film from tubular thermoplastic resin film
US3989785A (en) * 1972-11-21 1976-11-02 The Dow Chemical Company Method for the preparation of plastic film
US4203942A (en) * 1973-01-08 1980-05-20 Exxon Research & Engineering Co. Process for tubular water-bath polypropylene films
US3947170A (en) * 1974-04-05 1976-03-30 Windmoller & Holscher Rotary film blowhead for making tubular films of thermoplastic material
US4185148A (en) * 1976-05-17 1980-01-22 Mitsubishi Rayon Company Limited Process for producing the polypropylene film for electrical appliances
US4112034A (en) * 1977-05-05 1978-09-05 General Electric Company Biaxial film process and rotary apparatus therefor
US4195054A (en) * 1978-04-21 1980-03-25 Teepak, Inc. Method and apparatus for the manufacture of fibrous casing
US4285899A (en) * 1978-05-17 1981-08-25 Nortene Method and apparatus for making helical plastic members, and the members produced
US6033618A (en) * 1997-08-27 2000-03-07 Kalle Nalo Gmbh & Co. Kg Process and apparatus for producing a seamless cellulose-based tubular film by extrusion

Also Published As

Publication number Publication date
DE1629396A1 (de) 1972-05-25
FI46927B (fi) 1973-05-02
FR1501635A (fr) 1967-11-10
CH456129A (de) 1968-05-15
SE326026B (fi) 1970-07-13
GB1113300A (en) 1968-05-08
DK119848B (da) 1971-03-01
DE1629396B2 (de) 1974-02-07
DE1629396C3 (de) 1974-09-12
NL155476B (nl) 1978-01-16
FI46927C (fi) 1973-08-10
NL6616636A (fi) 1967-05-29

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